When is it too late to anneal?

[Revolver]

Although this is a real scenario my question is more from a conceptual standpoint. I have a batch of 308 brass with an unknown number of firings but a reliable history. On the last go-round about 10% developed split necks. My thinking is that most materials probably experience some sort of internal mechanical breakdown prior to failure. For example if you tear paper under a microscope you will likely see the fibers sustaining permanent damage before actual separation. When flexed many plastics can stretch a little (often turn white) prior to breaking. Both examples sound like a one way road so I would expect when brass cases are pushed to the brink, like these remaining 90%, then it may be too late to anneal? I'm not overly concerned about saving a small batch of old brass, I'm mostly curious for insight from a metallurgy/scientific perspective as well as from those who have experience in similar scenarios. Inquiring minds want to know! Thank you.

[Outpost75]

When you anneal brass in a batch in which some have already split, you will save some, and lose some.
Those close to failing will fail. Those which might be saved will be. If the split is better than 50-50 the effort is worth it.

[Walter Laich]

agree with above, try it and see what you get. it's better than not annealing

[Springfield]

I bought a batch of 44-40 bras that supposedly "hadn't been fired much". But when i started loading them I lost about 15% of them to split necks. So to try and save some I annealed them all. When I loaded the annealed cases the splits dropped to maybe 2%, and I have had very few fail after that with at least 5 loadings on them. So try it, it can't hurt and might save quite a few cases.

[runfiverun]

brass can get brittle just from sitting over time.
you could see it getting more brittle but you'd need to open the brass and look at the internal structure through a micro-scope.
when you anneal the brass your re-aligning the zinc and copper molecules.
much like firing the new case for the first time gives it a bit of stretch and makes the molecules take a directional set.
I like to use a full powered jacketed load for my first load on new brass to give it a chance to take a full chamber memory.

[DougGuy]

I have some PMC .308 brass of unknown to me history, it has been fired in a DPMS and I want to now use it in a bolt gun. Full length resize and then fireform. When would you anneal these?

[Revolver]

Thank you all for the input, quite reassuring that it's worth a go!

[Hickory]

.When is it too late to anneal?

When the last piece has split.

[Don Fischer]

I've got a lot of FA 49 Military 30-06 case's that I've used quite a bit. Never annealed and haven't had any split case's. I've only tried annealing a couple time's and don't think I'm very good at it and haven't found it necessary. With jacketed high pressure load's I dump case's when the primer pocket gets loose. I don't feel the cost of case's is so high as to fool with them getting much more use out of them.

[country gent]

Annealing softens brass and also relieves stress. On a lot of brass that has started to crack other cases may have small stress cracks that arnt visible to the eye already forming, annealing wont save these but the rest it may help. On my BPCR brass I anneal every 2-3 loadings. Alot of modern brass is annealed in the forming process sometimes several times depending on the case shape. But going from flat plate to cup to drawn cylinder heading up then necking and forming shoulder produces alot of work related stress and hardening in the process.

[runfiverun]

Doug I'd re-size then anneal and trim.
then load and shoot.
this would give you a fire-formed case that has had a sizing done on them.
when your seating the bullets/boolits in the cases right after the annealing you'll feel them seat with different amounts of resistance.
after the firing and another neck sizing you'll feel them get more uniform.

if you wanna see it working, measure the run-out on the new annealed batch and then again on the second loading.
your gonna find the run-out shrinks by about 50%.

on straight walled cases it seems the guy's that anneal more often are generally using black powder and the annealing helps them maintain a good seal to the chamber and a better boolit release due to the nature of the pressure rise of the powder. [and it's make up]

[fatelk]

brass can get brittle just from sitting over time.

Very true. How many besides me have had old reloads sitting around for two or three decades, and when you dig them out to shoot them you find lots of split necks?

[mold maker]

I once bought a full bandoleer of original either 303 or 30-40, and every round had split cases and necks. Everyone said I should have expected this.
When dealing with something you know nothing about, asking questions of those with experience will save face and pocketbook.
I later found out that incorrect annealing was the reason. I don't have a clue as to how it had been stored, but I'm sure the years hadn't helped.